1. Field of the Invention
This invention is related to the field of image processing and, more particularly, to structure from motion mechanisms.
2. Description of the Related Art
Various image processing mechanisms involve feature matching between images. For example, for camera motion estimation and structure from motion mechanisms, feature matching between images captured by the same camera in motion in a three dimensional (3D) space can be used to estimate the motion of the camera as well as the structures in the 3D space. Generally, more feature matches between pairs of images permits more accurate estimation of the camera motion and structure. Additionally, more feature matches can increase the likelihood that camera motion estimation and structure estimation will be successful.
Typically, the criteria for detecting a match between features in a pair of images are fairly strong. That is, the features must match closely in order to be declared a feature correspondence. There are several reasons for implementing strong matching criteria. For example, some structures in images are repetitive (e.g. the windows on a building). Accordingly, features that correspond to the windows result in numerous matches between the images, many of which are false matches (outliers) because features from two different windows on the building are matched. Such matches are often discarded because many of the matches are incorrect. Additionally, lens distortion affects features that are nearer the edge of a given image, and the distortion can prevent detection of correct feature correspondences where the feature in one or both of the images is near the edge.